A process for separating a water insoluble distillate from water vapor or steam is known comprising condensing the condensable components of the vapor by mixture condensation in a cooling fluid in which the cooling fluid mixed with the condensable vapors is separated into a distillate poor principal flow and a side flow enriched with distillate. Then the principal flow is cooled and recirculated.
Aqueous vapor which is loaded with water insoluble distillate, i.e. with fat and fat associated materials, is produced where steam distillation is carried out under vacuum, for example in the fatty acid fractionation or deodorization of fats and oils.
A large portion of the distillate is usually removed in a vapor wash device or scrubber.
However the vapor issuing from the vapor scrubber is still contaminated with distillate residue. Furthermore, noncondensable gases accompany it.
In practice it is known to reduce these aqueous vapors to the condensation pressure corresponding to the cooling water temperature by an ejector condenser and to condense them by mixture condensation. Thus a mixture made from vapor condensate, condensing working vapor and cooling water accumulates. It is also known to recirculate this cooling water by a cooling device and to split off a side flow rich in distillate from the circulation. In each case a water flow contaminated with distillate occurs.
The vapors can also be directly condensed by a cooling agent or electrolyte fed into the circulation, e.g a calcium chloride solution. Since a continuous diluton of the electrolyte occurs because of the condensable vapor constituents, fresh electrolyte must be continuously supplied. A salt containing side or auxiliary flow contaminated with distillate residue occurs as waste water.
The vapors can be condensed in a regenerative intermittently operating surface condenser which is maintained at the condensation temperature corresponding to the vacuum by ammonia, Freon or other refrigerants.
Since this condensation occurs below the triple point of water, the vapor condensate forms as ice on the surface which leads to intermittent operation by the continuously repeated cycle comprising condensation-icing, heating up and melting and cooling to the condensation temperature. In this process only the vapor condensate contaminated with distillate accumulates. The intermediate regenerative process requires additional energy consumption called for by the periodic heat up and melting and cooling of the condensed ice. All the usual problems of coupling continuously running processes, for example, those of the distillation with intermittent regeneratively running components, therefore results.